I. Field of the Invention
This invention relates to a tool for inserting and retrieving a measuring device within a high pressure pipeline and, in particular, to a simple apparatus adapted to quickly attach to on the stuffing box associated with an access valve of a high pressure pipeline in order to control the insertion and retrieval of a measuring device.
II. Description of the Prior Art
Various devices have been developed in order to test the fluid flow in high pressure pipelines. Generally, these tools utilize an access or gate valve built into the side wall of the pipeline. Because the fluid is pumped through the pipeline at high pressure, it is not only necessary that the probing tool prevent loss of pressure but also that it is sufficiently secured to prevent blowouts. Many insertion devices are secured to the access valve by mating flanges connected by a plurality of bolts. Alternate securing assemblies include mating threaded engagement although such constructions are normally not utilized in extreme pressure vessels. However, either of these mounting methods can be cumbersome requiring extensive tooling and assembly.
The mechanics for inserting the measuring probe through the access valve also widely vary. The most common, although the most complex, utilize hydraulic fluid pressure to manipulate a piston connected to the probe head. The piston and cylinder are normally positioned at the top of the tool thereby adding to the height of the tool requiring increased clearance. In addition, the support frame associated with the hydraulic assembly increases the weight of the tool thereby reducing its manipulability. Furthermore, the hydraulic assembly is subject to breakdown and fluid loss which can increase the chances of pressure loss or blowout.
Alternate insertion mechanisms include threaded stem and nut constructions which allow insertion or retraction by manipulation of a handwheel or a separate hand tool. Generally such devices comprise a probe head secured to the end of the threaded rod which is raised or lowered as the rod is rotated. As with the hydraulic assembly, clearance is needed above the tool for retraction of the threaded rod and probe.
Still other retraction tools utilize a gear box to manipulate the probe head into and out of the pressure pipeline. Because of the strength and securement necessary to prevent blowout and pressure loss, these gear assemblies can be large and heavy thereby adding to the overall weight of the tool.